Ambulatory measurement of cardiac activity can facilitate home health monitoring of older adults and of patients with a history of cardiovascular conditions. Evaluating cardiovascular performance of patients in ICU (intensive care unit) and hospital settings, in mobile ambulances, and at accident and trauma sites also involves or can involve ambulatory cardiac measurement.
Most current solutions for heart rate monitoring involve cumbersome equipment, such as heart rate recording belts to be worn around the chest, electrocardiogram (ECG) electrodes and leads, and in most cases electrical contact to the skin. However, such methods remain obtrusive, and are not optimal for long-term and ambulatory monitoring.
An alternative method of heart rate measurement uses heart sounds, conventionally measured with stethoscopes or phonocardiograph.
Detection and early warning of risk factors for and any incident of heart failure is vitally important in medicine, allied medical fields, residential care-giving, exercise venues and other settings. Heart failure can be caused by, and is at risk in case of, coronary artery disease, hypertension, valve disorder, past myocardial infarction, muscle disorder, congenital heart conditions, etc.
Current solutions for not only heart rate monitoring but also respiration monitoring are believed to involve cumbersome and expensive equipment e.g., respiration and heart rate monitoring belts to be worn around the chest, spirometers and canulas to be worn around the mouth and nose, and electrocardiogram (ECG) electrodes and leads to be taped on the body. Not only are these solutions obtrusive and expensive, but may also be too restrictive to be well-suited for ambulatory monitoring.
Noise mixed with signals received by the sensors used in heart monitoring, respiration monitoring, body motion and other monitoring applications can adversely affect the accuracy of each type of signal. Accordingly, methods for robust detection and separation of such signals in noisy conditions are desirable. Accuracy of heart rate detection is important in many commercial heart monitoring applications (e.g., heart rate monitors in exercise equipment, personal heart rate monitors, etc.) and medical heart monitoring applications (e.g., digital stethoscopes, mobile cardiac monitoring devices, etc.).
Simpler, more economical and more efficient methods and devices are desirable in the art for obtaining, isolating, determining and monitoring resting data and ambulatory data, such as robust, accurate detection of heart rate, timings of heart sounds (S1 and S2) and pathological cardiac conditions, and robust detection of respiration in connection with respiratory and pulmonary disorders, as well as data on body motion and ambulatory data and activity data.
Conventional approaches to address the bodily motion signal separation and/or removal problem are believed to involve multi-signal adaptive algorithms that need an additional motion signal reference recording typically from a secondary sensor. Also, the reference signal needs to be reasonably well correlated to the motion picked up by the primary sensor. Such arrangements are very difficult to establish in a real setting and can cause poor rejection of the motion signal and body motion artifacts. Some conventional single-channel de-noising techniques reinforce all major signal peaks and fail to distinguish body motions from heart sounds.
In addition to medical-related applications, solving the above problems could also help monitor older adults for unexpected changes in gait, for falls, for syncope (fainting), for accidents and trauma incidents. Fitness monitoring at home, in exercise venues, and in institutional care settings could also benefit.
Hemodynamic data also challenge the art to find methods and devices for obtaining, isolating, determining and monitoring more simply, economically and more efficiently. Hemodynamics as discussed herein includes the study of blood flow-related data directly or indirectly related to blood flow, such as: heart stroke volume, cardiac output, pre-ejection period, contractility (ability of heart to contract, inotropy), and related causal or caused bodily dynamics such as exercise and exercise recovery, and the Valsalva maneuver (such as when pushing or straining while holding one's breath, or otherwise doing the maneuver in a medical test).
Measurement of blood flow, hemodynamics and cardiovascular performance is integral to a holistic assessment of an individual's health. Specifically, patients with past conditions of heart disease like heart failure (potentially arising out of one or more of many causes like coronary artery disease, heart valve or heart muscle disorders, past myocardial infarction, hypertension etc.) may need constant monitoring in order to improve a person's quality of life via timely and appropriate diagnostic interventions. While the physiological mechanisms underlying these conditions are fairly well understood, the technology to monitor these physiological vitals needs considerable improvement.
Most current solutions for the measurement of blood flow and other hemodynamic parameters are believed to involve cumbersome and expensive equipment e.g., Impedance Cardiography (calls for electrodes to be connected on the skin), Doppler Echo Cardiography, Continuous Blood Pressure Monitoring etc. Not only are these solutions obtrusive and expensive, but may also be too restrictive to be well-suited for ambulatory monitoring applications.